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Abstract
In this book the difference operator 'd' is used to denote 'a small quantity of ...'. This 'small quantity' of one variable is almost always related to a 'small quantity' of another variable in some physical dependency. For example, irradiance is defined as E = dΦ/dA, which means that a small amount of flux dΦ impinges on a small area dA, resulting in an irradiance of E. 'Small' is defined as the extent or domain over which the quantity, or any of its dependent quantities, does not vary significantly. Because any finite-sized quantity varies over a finite-sized domain, the d operation is only valid over an infinitely small domain dA= limΔA→0 ΔA. In this book the difference operator 'd' is used to denote 'a small quantity of ...'. This 'small quantity' of one variable is almost always related to a 'small quantity' of another variable in some physical dependency. For example, irradiance is defined as E = dΦ/dA, which means that a small amount of flux dΦ impinges on a small area dA, resulting in an irradiance of E. 'Small' is defined as the extent or domain over which the quantity, or any of its dependent quantities, does not vary significantly. Because any finite-sized quantity varies over a finite-sized domain, the d operation is only valid over an infinitely small domain dA= limΔA→0 ΔA.
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CHAPTER 2
39 PAGES


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